Pandemic Phase-Adjusted Analysis of COVID-19 Outcomes Reveals Reduced Intrinsic Vulnerability and Substantial Vaccine Protection From Severe Acute Respiratory Syndrome Coronavirus 2 in Patients With Breast Cancer
Authors: Marco Tagliamento, Alessandra Gennari, Matteo Lambertini, Ramon Salazar, Nadia Harbeck, Lucia Del Mastro, Juan Aguilar-Company, Mark Bower, Rachel Sharkey, Alessia Dalla Pria, Andrea Plaja, Amanda Jackson, Jasmine Handford, Ailsa Sita-Lumsden, Clara Martinez-Vila, Marta Matas, Ana Miguel Rodriguez, Bruno Vincenzi, Giuseppe Tonini, Alexia Bertuzzi, Joan Brunet, Paolo Pedrazzoli, Francesca D'Avanzo, Federica Biello, Alasdair Sinclair, Alvin J.X. Lee, Sabrina Rossi, Gianpiero Rizzo, Oriol Mirallas, Isabel Pimentel, Maria Iglesias, Ana Sanchez de Torre, Annalisa Guida, Rossana Berardi, Alberto Zambelli, Carlo Tondini, Marco Filetti, Francesca Mazzoni, Uma Mukherjee, Nikolaos Diamantis, Alessandro Parisi, Avinash Aujayeb, Aleix Prat, Michela Libertini, Salvatore Grisanti, Maura Rossi, Federica Zoratto, Daniele Generali, Cristina Saura, Gary H. Lyman, Nicole M. Kuderer, David J. Pinato, Alessio Cortellini
Journal: Journal of Clinical Oncology (2023)

PURPOSE Although representing the majority of newly diagnosed cancers, patients with breast cancer appear less vulnerable to COVID-19 mortality compared with other malignancies. In the absence of patients on active cancer therapy included in vaccination trials, a contemporary real-world evaluation of outcomes during the various pandemic phases, as well as of the impact of vaccination, is needed to better inform clinical practice. METHODS We compared COVID-19 morbidity and mortality among patients with breast cancer across prevaccination (February 27, 2020-November 30, 2020), Alpha-Delta (December 1, 2020-December 14, 2021), and Omicron (December 15, 2021-January 31, 2022) phases using OnCovid registry participants (ClinicalTrials.gov identifier: NCT04393974 ). Twenty-eight-day case fatality rate (CFR 28 ) and COVID-19 severity were compared in unvaccinated versus double-dosed/boosted patients (vaccinated) with inverse probability of treatment weighting models adjusted for country of origin, age, number of comorbidities, tumor stage, and receipt of systemic anticancer therapy within 1 month of COVID-19 diagnosis. RESULTS By the data lock of February 4, 2022, the registry counted 613 eligible patients with breast cancer: 60.1% (n = 312) hormone receptor–positive, 25.2% (n = 131) human epidermal growth factor receptor 2–positive, and 14.6% (n = 76) triple-negative. The majority (61%; n = 374) had localized/locally advanced disease. Median age was 62 years (interquartile range, 51-74 years). A total of 193 patients (31.5%) presented ≥ 2 comorbidities and 69% (n = 330) were never smokers. In total, 392 (63.9%), 164 (26.8%), and 57 (9.3%) were diagnosed during the prevaccination, Alpha-Delta, and Omicron phases, respectively. Analysis of CFR 28 demonstrates comparable estimates of mortality across the three pandemic phases (13.9%, 12.2%, 5.3%, respectively; P = .182). Nevertheless, a significant improvement in outcome measures of COVID-19 severity across the three pandemic time periods was observed. Importantly, when reported separately, unvaccinated patients from the Alpha-Delta and Omicron phases achieved comparable outcomes to those from the prevaccination phase. Of 566 patients eligible for the vaccination analysis, 72 (12.7%) were fully vaccinated and 494 (87.3%) were unvaccinated. We confirmed with inverse probability of treatment weighting multivariable analysis and following a clustered robust correction for participating center that vaccinated patients achieved improved CFR 28 (odds ratio [OR], 0.19; 95% CI, 0.09 to 0.40), hospitalization (OR, 0.28; 95% CI, 0.11 to 0.69), COVID-19 complications (OR, 0.16; 95% CI, 0.06 to 0.45), and reduced requirement of COVID-19–specific therapy (OR, 0.24; 95% CI, 0.09 to 0.63) and oxygen therapy (OR, 0.24; 95% CI, 0.09 to 0.67) compared with unvaccinated controls. CONCLUSION Our findings highlight a consistent reduction of COVID-19 severity in patients with breast cancer during the Omicron outbreak in Europe. We also demonstrate that even in this population, a complete severe acute respiratory syndrome coronavirus 2 vaccination course is a strong determinant of improved morbidity and mortality from COVID-19.